HTML5 Canvas阴影使用方法实例演示

当前位置：首页 > 范文|应用文 > IT技术专栏 > 网页制作

来源：阅读：1038 次日期：2016-07-13 13:42:11

温馨提示：小编为您整理了“HTML5 Canvas阴影使用方法实例演示”,方便广大网友查阅！

HTML5 Canvas中提供了设置阴影的四个属性值可以实现阴影文字、3D拉影效果、边缘模糊效果文字，具体的演示代码如下，想学习的朋友可以参考下

HTML5 Canvas中提供了设置阴影的四个属性值分别为：

context.shadowColor = “red” 表示设置阴影颜色为红色

context.shadowOffsetX = 0表示阴影相对TEXT的水平距离，0表示两者水平位置重合

context.shadowOffsetY = 0表示阴影相对TEXT的垂直距离，0表示两者垂直位置重合

context.shadowBlur = 10 阴影模糊效果，值越大模糊越厉害。

一个最简单的带有阴影的矩形代码如下：

context.shadowColor = "RGBA(127,127,127,1)";

context.shadowOffsetX = 3;

context.shadowOffsetY = 3;

context.shadowBlur = 0;

context.fillStyle = "RGBA(0, 0, 0, 0.8)";

context.fillRect(10, hh+10, 200,canvas.height/4-20);

效果如下：

阴影文字：

只要设置shadowOffsetX与shadowOffsetY的值，当值都正数时，阴影相对文字的右下

方偏移。当值都为负数时，阴影相对文字的左上方偏移。

3D拉影效果：

在同一位置不断的重复绘制文字同时改变shadowOffsetX、shadowOffsetY、shadowBlur

的值，从小到大不断偏移不断增加，透明度也不断增加。就得到了拉影效果文字。

边缘模糊效果文字：

在3D拉影效果的基础上在四个方向重复，就得到了边缘羽化的文字效果。

运行效果：

序代码：

代码如下:

<!DOCTYPE html>

<html>

<head>

<title>Canvas Clip Demo</title>

var ctx = null; // global variable 2d context

var imageTexture = null;

window.onload = function() {

var canvas = document.getElementById("text_canvas");

console.log(canvas.parentNode.clientWidth);

canvas.width = canvas.parentNode.clientWidth;

canvas.height = canvas.parentNode.clientHeight;

if (!canvas.getContext) {

console.log("Canvas not supported. Please install a HTML5 compatible browser.");

return;

}

var context = canvas.getContext('2d');

// section one - shadow and blur

context.fillStyle="black";

context.fillRect(0, 0, canvas.width, canvas.height/4);

context.font = '60pt Calibri';

context.shadowColor = "white";

context.shadowOffsetX = 0;

context.shadowOffsetY = 0;

context.shadowBlur = 20;

context.fillText("Blur Canvas", 40, 80);

context.strokeStyle = "RGBA(0, 255, 0, 1)";

context.lineWidth = 2;

context.strokeText("Blur Canvas", 40, 80);

// section two - shadow font

var hh = canvas.height/4;

context.fillStyle="white";

context.fillRect(0, hh, canvas.width, canvas.height/4);

context.font = '60pt Calibri';

context.shadowColor = "RGBA(127,127,127,1)";

context.shadowOffsetX = 3;

context.shadowOffsetY = 3;

context.shadowBlur = 0;

context.fillStyle = "RGBA(0, 0, 0, 0.8)";

context.fillText("Blur Canvas", 40, 80+hh);

// section three - down shadow effect

var hh = canvas.height/4 + hh;

context.fillStyle="black";

context.fillRect(0, hh, canvas.width, canvas.height/4);

for(var i = 0; i < 10; i++)

{

context.shadowColor = "RGBA(255, 255, 255," + ((10-i)/10) + ")";

context.shadowOffsetX = i*2;

context.shadowOffsetY = i*2;

context.shadowBlur = i*2;

context.fillStyle = "RGBA(127, 127, 127, 1)";

context.fillText("Blur Canvas", 40, 80+hh);

}

// section four - fade effect

var hh = canvas.height/4 + hh;

context.fillStyle="green";

context.fillRect(0, hh, canvas.width, canvas.height/4);

for(var i = 0; i < 10; i++)

{

context.shadowColor = "RGBA(255, 255, 255," + ((10-i)/10) + ")";

context.shadowOffsetX = 0;

context.shadowOffsetY = -i*2;

context.shadowBlur = i*2;

context.fillStyle = "RGBA(127, 127, 127, 1)";

context.fillText("Blur Canvas", 40, 80+hh);

}

for(var i = 0; i < 10; i++)

{

context.shadowColor = "RGBA(255, 255, 255," + ((10-i)/10) + ")";

context.shadowOffsetX = 0;

context.shadowOffsetY = i*2;

context.shadowBlur = i*2;

context.fillStyle = "RGBA(127, 127, 127, 1)";

context.fillText("Blur Canvas", 40, 80+hh);

}

for(var i = 0; i < 10; i++)

{

context.shadowColor = "RGBA(255, 255, 255," + ((10-i)/10) + ")";

context.shadowOffsetX = i*2;

context.shadowOffsetY = 0;

context.shadowBlur = i*2;

context.fillStyle = "RGBA(127, 127, 127, 1)";

context.fillText("Blur Canvas", 40, 80+hh);

}

for(var i = 0; i < 10; i++)

{

context.shadowColor = "RGBA(255, 255, 255," + ((10-i)/10) + ")";

context.shadowOffsetX = -i*2;

context.shadowOffsetY = 0;

context.shadowBlur = i*2;

context.fillStyle = "RGBA(127, 127, 127, 1)";

context.fillText("Blur Canvas", 40, 80+hh);

}

</script>

</head>

<body>

<h1>HTML5 Canvas Clip Demo - By Gloomy Fish</h1>

<pre>Fill And Stroke Clip</pre>

</div>

</body>

</html>

上一篇：使用HTML5拍照示例代码

下一篇：HTML5 Canvas自定义圆角矩形与虚线示例代码

手机网站地址：HTML5 Canvas阴影使用方法实例演示

由于各方面情况的不断调整与变化，提供的所有考试信息和咨询回复仅供参考，敬请考生以权威部门公布的正式信息和咨询为准！